SYMPOSIA PAPER Published: 01 January 1986

Irradiation Effects in Reactor Pressure Vessel Steels: A Nuclear Regulatory Commission Perspective


The embrittling effect of neutron irradiation on reactor pressure vessel steel and welds has a significant impact on the regulation of reactors by the U.S. Nuclear Regulatory Commission (NRC). Because the NRC is concerned with the continuing integrity and safety of the reactor's primary system, the neutron-irradiation-induced loss of fracture toughness and ductility must be carefully documented, understood, and controlled to assure that despite such loss, there is always a sufficient reserve of toughness and ductility to preclude crack initiation and uncontrolled propagation in the unlikely event of an accident. Aspects of embrittlement important to the NRC, which are discussed herein, include prediction of the transition temperature and upper-shelf-energy levels at critical vessel locations for the setting of pressure-temperature limits, for analysis of accident loadings such as pressurized thermal shock, and for evaluation of flaws found in inspection. Also discussed are the use of embrittlement-related neutron dosimetry and evaluation of vessel annealing.

Author Information

Serpan, CZ
Nuclear Regulatory Commission, Washington, DC
Randall, PN
Nuclear Regulatory Commission, Washington, DC
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Developed by Committee: E10
Pages: 5–12
DOI: 10.1520/STP23025S
ISBN-EB: 978-0-8031-4975-5
ISBN-13: 978-0-8031-0473-0